RE: Are IPv6 auto-configured addresses transient?

["Hemant Singh (shemant)" <shemant at cisco.com>]

>-----Original Message-----
>From: ipv6-bounces at ietf.org [mailto:ipv6-bounces at ietf.org] On Behalf Of
Brian Haberman
>Sent: Friday, October 16, 2009 1:35 PM
>To: Margaret Wasserman
>Cc: ipv6 at ietf.org
>Subject: Re: Are IPv6 auto-configured addresses transient?


>I *think* that Vijay is asking a more general question about 
>applications rather than how to get IPv6 addresses (or service).  If I 
>interpreted his earlier comments correctly, he is asking what does an 
>application know about an address that it is using.  For example, if 
>Vijay's application is long-lived would it be affected by an address 
>becoming deprecated and no longer reachable.  In this case, the address

>stays reachable for some period of time until the deprecated prefix is 
>removed from the routing system.

I don't see any problem here.  Till a specific long-lived application
screw case is described, I am not convinced the app needs to know
anything related to lifetimes of addresses.  On an IPv6 node, if
anything related to the addresses on a network interface changes, the
changes will affect the network interfaces the app is using.  Even in
IPv4, if an app is using an IP address of a network interface on the
node, the app tracks changes of the IP address on the network interface
- so IPv6 apps should do the same.     

>I suppose there is a related question as to how an application that
uses 
>IP addresses in referrals should behave.  Would an application find it 
>useful to know the lifetime associated with the auto-configured
addresses?

It may make sense that referrals for IPv6 do not merely use IP addresses
but switch to using a PIO (Prefix Information Option from RFC 4861) per
address.  The PIO contains the Prefix Lifetime.

Hemant